Fiber optic cables are favored for modern data communication. Fiber optic cable offers large bandwidth for high-speed data transmission. Signals can be sent farther than across copper cables without the need to “refresh” or strengthen the signal. Fiber optic cables offer superior resistance to electromagnetic noise, such as from adjoining cables. In addition, fiber optic cables require far less maintenance than metal cables, thereby making fiber optic cables more cost effective.
Optical fiber is made of a core that is surrounded by a cladding layer. The core is the physical medium that transports optical data signals from an attached light source to a receiving device. The core is a single continuous strand of glass or plastic that is measured (in microns) by the size of its outer diameter. The larger the core, the more light the cable can carry. All fiber optic cable is sized according to its core diameter. The three diameters of the most commonly available multimode cores are 50-micron, 62.5-micron, and 100-micron, although single-mode cores may be as small as 8-10 microns in diameter. The cladding is a thin layer that surrounds these micrometer sized fiber cores. It is the core-cladding boundary that contains the light waves within the core by causing the high-angle reflection as measured relative to a line perpendicular to this boundary, such as a core-diametral line, enabling data to travel throughout the length of the fiber segment. Typically, the core and cladding are made of high-purity silica glass. The light signals remain within the optical fiber core due to total or near-total internal reflection within the core, which is caused by the difference in the refractive index between the cladding and the core.
The cladding is typically coated with a layer of acrylate polymer or polymide, thereby forming an insulating jacket. This insulating jacket protects the optic fiber from damage. This coating also reinforces the optic fiber core, absorbs mechanical shocks, and provides extra protection against excessive cable bends. These insulating jacket coatings are measured in microns and typically range from 250 microns to 900 microns.
Strengthening fibers are then commonly wrapped around the insulating jacket. These fibers help protect the core from crushing forces and excessive tension during installation. The strengthening fibers can be made of KEVLAR™ for example. An outer cable jacket is then provided as the outer layer of the cable. The outer cable jacket surrounds the strengthening fibers, the insulating jacket, the cladding and the optic fiber core. Typically, the outer cable jacket is colored orange, black, or yellow.
It is highly desirable to develop advanced optic fibers that can transmit data at higher rates, thereby increasing data bandwidth.